Signorino U.S. Pat. No. 3,981,984 provides an edible concentrated pigment suspension that is shipped, for example, to a pharmaceutical manufacturer who mixes it with a polymer solution to form a coating suspension which may be used for coating tablets and the like. The pigment suspension, polymer solution, and coating suspension are in a non-aqueous solvent.
It has long been desired to provide a dry edible film coating composition which can be constituted with solvent by the customer, that eliminates the problem of shipping of pigment dispersions containing aqueous or non-aqueous solvents and thereby eliminates the problems caused by solvents, and also makes shipping less expensive by eliminating the weight of the solvents.
It is known in the prior art to mix a dry polymer powder with pigment particles, and to grind the mixture to obtain a dry polymer-pigment mixture which is then ground into a fine powder mixture. However, when this fine polymer-pigment mixture is stirred into water and dispersed, the polymer makes lumps and fish eyes because it agglomerates, and the result is not really a uniform dispersion. Accordingly, when this polymer-pigment dispersion is used as a coating dispersion and is coated onto tablets and the like, unless the dispersion is left to solvate for a considerable period of time like overnight, the coating is lumpy and not uniform and is therefore undesirable.